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<head><meta charset="utf-8"><title>weird regression · t-compiler/help · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/index.html">t-compiler/help</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/weird.20regression.html">weird regression</a></h3>

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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/weird%20regression/near/242482305" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Noah Lev <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/weird.20regression.html#242482305">(Jun 13 2021 at 01:15)</a>:</h4>
<p>There's a rustdoc bug (<a href="https://github.com/rust-lang/rust/issues/86208">#86208</a>) that is present on beta and nightly, but is not on stable. However, a manual (<code>--prompt</code>) cargo-bisect-rustc bisection pointed to 2020-03-11 as the regression date, which is more than a year ago. I suspect that <a href="https://github.com/rust-lang/rust/issues/66364">#66364</a> is the PR that caused the regression based on looking through the commits in that nightly.</p>
<p>Does anyone have an idea of how a regression could have occurred more than a year ago but not be present on stable? Thanks!</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/weird%20regression/near/242482474" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Noah Lev <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/weird.20regression.html#242482474">(Jun 13 2021 at 01:20)</a>:</h4>
<p>I also wonder if <a href="https://github.com/rust-lang/rust/commit/f94360fd83b49554b6c26999a0030e9cfe800f32">f94360fd83b49554b6c26999a0030e9cfe800f32</a> could be related somehow? It landed in between stable and beta, but the bisection doesn't point to it, so <span aria-label="shrug" class="emoji emoji-1f937" role="img" title="shrug">:shrug:</span></p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/weird%20regression/near/242488242" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Eric Huss <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/weird.20regression.html#242488242">(Jun 13 2021 at 03:58)</a>:</h4>
<p><span class="user-mention" data-user-id="307537">@Noah Lev</span> Whether or not it works depends on if the rust-src component is installed, so you'll need to use <code>--with-src</code> when bisecting (and make sure to clean up any toolchains if you used <code>--preserve</code>).</p>
<p>It is a little confusing because it has switched between working/not working a few times. From what I can tell, it started working in nightly-2020-04-04 (because of <a href="https://github.com/rust-lang/rust/issues/70642">#70642</a>), and has stopped working again in nightly-2021-04-30 (because of <a href="https://github.com/rust-lang/rust/issues/84233">#84233</a>).</p>
<p>So, the most recent regression is due to <a href="https://github.com/rust-lang/rust/issues/84233">#84233</a>.</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/weird%20regression/near/242521848" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Noah Lev <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/weird.20regression.html#242521848">(Jun 13 2021 at 17:39)</a>:</h4>
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<p>It is a little confusing because it has switched between working/not working a few times. From what I can tell, it started working in nightly-2020-04-04 (because of <a href="https://github.com/rust-lang/rust/issues/70642">#70642</a>), and has stopped working again in nightly-2021-04-30 (because of <a href="https://github.com/rust-lang/rust/issues/84233">#84233</a>).</p>
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<p>Ah, that makes sense! I didn't think of the possibility of it switching between working and not working, which would definitely confuse cargo-bisect-rustc (and me).</p>
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<p>So, the most recent regression is due to <a href="https://github.com/rust-lang/rust/issues/84233">#84233</a>.</p>
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<p>Thank you for finding that!</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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